There is a small lump in my ?

Ok, I'm seventeen years old, i was in the process of masturbation, i don't know if thats important, but I'm going to give you alot more details than you probably need to know. I am a virgin, If that matters. I was rubbing my , and my at the same time, i felt a lump in my left . I was laying on my right side, and you can feel it, it hurts a little from me poking it. I highly doubt its cancer, the chances of that are slim to none at my age, and although my grandmother did have cancer, i don't think its hereditary. I will tell my mom about it tomorrow, but i have always been a Drama queen. What i want to know is, what could it be? and i want some reurances that its not cancer, cuz that scares me. I think i gave all the info thats needed. OH!! and if i lay on my left side, poking my right in the same way, it does not have a lump, so i know its not suppose to be there... i don't think. THANKS!!